Help from the experts please

[Ditchlight]

It's been a while since I posted on here looking for help , but due to some hard driving my nephew pretty much destroyed every cup imaginable on his Savage Flux XS, so it's been out of commission. Now while I was replacing all those parts I also decided to replace the pinion gear to the 24T-48P and the idler gear 32-T-60T-48P. I have noticed the motor has gotten significantly louder, is that normal when changing out gears? I checked and the meshing looks good to me, but I am new to being a mechanic for RC's and figured I would ask before this became another problem I had to fix.

Thanks for your input

Patrick

 

[hpicelery]

I changed my idler gear to the 32T/60T idler and the 26T pinion, and I didn't notice a major change in the noise the truck made, though I'm only running 2S batteries.

Did you make sure to position the motor in the correct mounting holes as shown on page 26 of the manual?
http://hpiracing.world/assets/documents/instruction_manuals/110712-savage_xs-glb-m-v4.pdf

If so, then your gear mesh is fine.

Some questions that might be relevant: Why the gear change? Are you running 3S LiPo packs? Did you switch from 2S to 3S at the same time as the gear change? Are you running bigger tires?

 

[Ditchlight]

I double checked the mounting, pretty sure I did use the correct mounting as I needed the manual for everything I have changed or had to replace. Although I noticed the center shaft, with the drive gear has a fair amount of play in it around, not so much back and forth, to the point where I can put a bit of pressure on it and it won't even touch the idler gear. Is that supposed to be loose or is there a way to lock that center in place too?

Always ran a 2s and a 3s LiPo battery in the car, he drives to the field and gets warmed up with the 2s, then puts in the 3s when the 2 is done. So I did the upgrade because it was recommended on the box. And he does have a bigger set of tires also that he uses on occasion.

 

[hpicelery]

You're talking about the gear that's on the same shaft as the transmission drive cups, right? Not the motor?

If so, that's definitely not normal. It's possible that the bearings supporting that shaft are shot. You'll have to take the transmission out to see for sure (a pain, I know). You can replace them with HPI part numbers B022 and B030, or you can go to FastEddyBearings.com and get a 5x11x4mm and 10x15x4mm rubber sealed bearing for a buck apiece.

 

[Ditchlight]

The gear on the left side is the one with the play in it. Still new to this so all I had was the names of parts and pieces on #6, pg.28 of the manual

 

[hpicelery]

Are you saying that the shaft has that amount of play with the transmission open, or fully assembled? I wouldn't be surprised if you can wobble the shaft around when it's only supported at one end. That's normal. When the transmission is fully assembled, can you still wiggle the shaft around? If it still moves around a lot, then you might have bad bearings like I said. Otherwise, you're probably fine.

 

[Ditchlight]

Yes the wobble was with it disassembled, I guess I was just grasping for solutions there, I will cut him loose with the way it is and just keep an eye on it and see how if fairs. Thnx for your input hpicelery

 

[hpicelery]

Not a problem. That was honestly going to be my next suggestion... if everything looks like it's in place, just go run it and see what happens!

 

[Ditchlight]

So just an update, after about 20ft, the gear stopped catching and was just spinning, so does that help narrow the problems down a bit more at all for anyone?

 

[hpicelery]

That's unfortunate. You could have stripped a gear or fried a bearing, but the most likely explanation is that your pinion gear set screw came loose. If that's the case, make sure the screw is tightened onto the flat part of the motor shaft and secured with threadlock. From my own experience, if you don't threadlock that screw it won't stay tight for long.